1 //===----------------------------------------------------------------------===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 9 #ifndef _LIBCPP___COMPARE_COMPARE_PARTIAL_ORDER_FALLBACK 10 #define _LIBCPP___COMPARE_COMPARE_PARTIAL_ORDER_FALLBACK 11 12 #include <__compare/ordering.h> 13 #include <__compare/partial_order.h> 14 #include <__config> 15 #include <__type_traits/decay.h> 16 #include <__type_traits/is_same.h> 17 #include <__utility/forward.h> 18 #include <__utility/priority_tag.h> 19 20 #ifndef _LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER 21 # pragma GCC system_header 22 #endif 23 24 _LIBCPP_BEGIN_NAMESPACE_STD 25 26 #if _LIBCPP_STD_VER >= 20 27 28 // [cmp.alg] 29 namespace __compare_partial_order_fallback { 30 struct __fn { 31 template <class _Tp, class _Up> 32 requires is_same_v<decay_t<_Tp>, decay_t<_Up>> 33 _LIBCPP_HIDE_FROM_ABI static constexpr auto __go(_Tp&& __t, _Up&& __u, __priority_tag<1>) noexcept( 34 noexcept(std::partial_order(std::forward<_Tp>(__t), std::forward<_Up>(__u)))) 35 -> decltype(std::partial_order(std::forward<_Tp>(__t), std::forward<_Up>(__u))) { 36 return std::partial_order(std::forward<_Tp>(__t), std::forward<_Up>(__u)); 37 } 38 39 template <class _Tp, class _Up> 40 requires is_same_v<decay_t<_Tp>, decay_t<_Up>> 41 _LIBCPP_HIDE_FROM_ABI static constexpr auto __go(_Tp&& __t, _Up&& __u, __priority_tag<0>) noexcept(noexcept( 42 std::forward<_Tp>(__t) == std::forward<_Up>(__u) ? partial_ordering::equivalent 43 : std::forward<_Tp>(__t) < std::forward<_Up>(__u) ? partial_ordering::less 44 : std::forward<_Up>(__u) < std::forward<_Tp>(__t) 45 ? partial_ordering::greater 46 : partial_ordering::unordered)) 47 -> decltype(std::forward<_Tp>(__t) == std::forward<_Up>(__u) ? partial_ordering::equivalent 48 : std::forward<_Tp>(__t) < std::forward<_Up>(__u) ? partial_ordering::less 49 : std::forward<_Up>(__u) < std::forward<_Tp>(__t) 50 ? partial_ordering::greater 51 : partial_ordering::unordered) { 52 return std::forward<_Tp>(__t) == std::forward<_Up>(__u) ? partial_ordering::equivalent 53 : std::forward<_Tp>(__t) < std::forward<_Up>(__u) ? partial_ordering::less 54 : std::forward<_Up>(__u) < std::forward<_Tp>(__t) 55 ? partial_ordering::greater 56 : partial_ordering::unordered; 57 } 58 59 template <class _Tp, class _Up> 60 _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Tp&& __t, _Up&& __u) const 61 noexcept(noexcept(__go(std::forward<_Tp>(__t), std::forward<_Up>(__u), __priority_tag<1>()))) 62 -> decltype(__go(std::forward<_Tp>(__t), std::forward<_Up>(__u), __priority_tag<1>())) { 63 return __go(std::forward<_Tp>(__t), std::forward<_Up>(__u), __priority_tag<1>()); 64 } 65 }; 66 } // namespace __compare_partial_order_fallback 67 68 inline namespace __cpo { 69 inline constexpr auto compare_partial_order_fallback = __compare_partial_order_fallback::__fn{}; 70 } // namespace __cpo 71 72 #endif // _LIBCPP_STD_VER >= 20 73 74 _LIBCPP_END_NAMESPACE_STD 75 76 #endif // _LIBCPP___COMPARE_COMPARE_PARTIAL_ORDER_FALLBACK 77